The present invention relates generally to the manufacture of electromechanical machines, such as electric motors. More particularly, the invention relates to an improved apparatus for welding lamination stacks to produce a magnetically-permeable core for use in an electromechanical machine.
Electric motors and other electromechanical machines are generally constructed having at least one magnetically-permeable core. For example, induction motors are typically constructed having a cylindrical stator core. The inner circumference of the stator core defines a plurality of parallel slots in which electrical windings are maintained. As is well known, current flow through the windings produces a rotating magnetic field which the rotor of the machine will tend to follow.
To manufacture the core, a relatively large number of laminations may be stacked on a welding arbor to a desired height. Often, the welding arbor is configured to radially expand against the inner circumference of the stack such that the individual laminations will be concentrically aligned. A welding device is utilized to produce a plurality of vertical welds at predetermined angular locations on the outer circumference of the stack. As a result, the laminations will be connected together into a core body that can be handled as a unit.
The dimensions of the core will vary depending on the particular motor into which it is to be installed. For example, parameters such as outer diameter, inner diameter and winding slot spacing are dictated by specific motor criteria. Typically, a different welding arbor will be required for each of the various core configurations.
In the past, systems have been employed in order to permit the use of different welding arbors with a single welding machine. It has been generally difficult with these systems to store and retrieve the different arbors without delays in the manufacturing process. For example, one known system uses a horizontal storage system which requires rotating through multiple arbors in order to retrieve a particular arbor that has been selected. In addition, it has often been necessary to set-up the welding system each time a different core was to be produced.